Modern day computer systems often service a significant number of end user devices. Since these end user devices, or terminals, represent an important element of user productivity, efforts are constantly under way to improve their ease of use. Perhaps the most significant measure of a device's "usability" is its response time. Though response time is often perceived to be a function of the end user device itself, the rapidity of response, or lack thereof, is typically a function of the host unit. Therefore, the information sent by the host unit is of particular importance. When discussing the information that is sent from a host unit to a terminal, the nomenclature used is that of a data stream. A data stream can be conceptualized as a "flow" of information. The information flow, usually quantified in bytes, is what a user sees on their terminal's display screen. Beyond the raw information that is to be transmitted to the terminal, specific data stream architectures typically involve commands and orders that facilitate positioning the information on the display screen and/or emphasizing the appearance of the information (e.g., color, highlighting, etc.). Since the amount of information that is sent from the host unit to the terminal has a direct bearing on response time, computer designers are constantly looking for ways to reduce the necessary information flow. One way to reduce the information sent to the terminal is to send only the information that does not already exist on the terminal's display. An example of this reduction technique is to compare the terminal's existing screen image to the next screen image and route only the differences. Another similar technique is to monitor the terminal's existing image and then route only the updates.
While these optimization techniques have reduced response time somewhat, the amount of unnecessary information that is routed to the terminal remains significant. There is time and productivity lost with every unnecessary byte of information that flows to the terminal. This problem becomes even more acute when one considers computer systems that support non-native devices (i.e., terminal devices that were originally designed to operate on a different system). One example is the support of IBM 3270 terminal devices by computer systems that use the IBM 5250 data stream protocol. When a 3270 device is connected to a 5250 system, each and every instruction (e.g., a non-data entity) of the 5250 data stream must be translated into an instruction that can be understood by the 3270 device. In some cases, one 5250 command translates into several 3270 commands. This has the drastic result of increasing response time rather than decreasing response time.